Allergenic reactions to natural rubber latex products have been recognized for several decades and range from allergic contact dermatitis to systemic allergic reactions. It has been determined that such allergic reactions are IgE-mediated and are due to allergenic proteins found in natural rubber latex. See, for example, Truscott, W., Latex Allergy 15(1):89–121, 1995. Products made from natural rubber latex are found everywhere and are used in various industrial, commercial, medical, and home applications. Medical products made of natural rubber latex include exam and surgical gloves, anesthesia mask and bags, catheters, injection ports, dental dams, condoms, diaphragms, balloons, and blood pressure cuffs. Non-medical natural rubber latex products include toy balloons, household gloves, and foam mattresses and pillows. During the manufacture of these products, naturally occurring proteins in natural rubber latex can migrate to the surface and potentially cause an allergenic reaction in the user.
Several protocols for removing protein allergens from finished latex articles have been proposed, but all suffer from functional or economic shortcomings. For example, wet-stripping latex gloves off the molds is reported to remove a large amount of protein allergens, but adapting existing facilities to accommodate wet-stripping is extremely expensive. Using a post-stripping process such as chlorination to degrade protein allergens has also been proposed, but such a process must be carefully monitored in order to prevent adversely impacting the physical properties of the latex article. Washing the finished articles after oven curing has also been proposed but is also prohibitively expensive to incorporate into conventional manufacturing environments. Treatment of the finished article with protease enzymes has been proposed. However, as noted below, such a treatment fails to eliminate the allergenicity of latex articles. See Truscott, W., Latex Allergy 15 (1): 89–121, 1995.
U.S. Pat. No. 5,777,004 describes a method of neutralizing protein allergens in natural rubber latex by treating a latex emulsion with protease and peptidase enzymes whereby the protein allergens are degraded so as to be rendered non-allergenic to humans. Although this method provides an economically feasible protocol without serious adverse affects to the physico-mechanical properties of finished latex articles, the problem remains that there is no way to control the extent of the hydrolytic reaction, i.e., there is no way to stop the reaction after the desired amount of hydrolysis has been obtained. Continued hydrolysis of the latex emulsion by protease and peptidase enzymes can lead to instability of the latex emulsion.
U.S. Pat. No. 6,380,283 describes a method of treating natural rubber latex that involves enzyme treatment utilizing a chemical stabilizer and treatment with antioxidants that allows for chlorination processing. However, the problem of controlling the extent of hydrolysis remains and is not addressed.